Dynamics GP - Manufacturing - "You do not have access priveleges to edit this field" after cancelling a linked MO, and trying to cancel the SOP quantity

SOP/MOP Link
https://groups.google.com/forum/#!topic/microsoft.public.greatplains/_MsTrRLp2GQ
http://microsoft.public.greatplains.narkive.com/92kddrvO/sop-mop-linked-orders

Cause:
This occurs when you have created an SOP order, auto-generated an MO, and then cancel the MO, and try to cancel the Order Quantity.
This is because you have not defined a security set to manage the Edit SO Qty option on the SOP Manufacturing setup.

Solution:

• Create Security Set
• Manufacturing>Setup>System>Process Security
• Create set
• Set to password, set a password
• Sales Order Processing Setup>Additional>Manufacturing Sales Order
• Prefs. There's a field called "Edit SO QTY's when MO is attached Process
• Security". You can choose a "security set" to authorize users to edit the
• sales line quantities.